Drop shape analysis (DSA) is an image analysis method for determining the contact angle from the shadow image of a sessile drop and the surface tension or interfacial tension from the shadow image of a pendant drop. – A drop is metered onto a solid sample (sessile drop) or is located at the tip of a needle (pendant drop). – An image of the drop is recorded with the help of a camera and transferred to the drop shape analysis software. – A contour recognition is initially carried out based on a grey-scale analysis of the image. – In the second step, a geometrical model describing the drop shape is fitted to the contour.